PIC16CR58A-04I/SO View Datasheet(PDF) - Microchip Technology
Part Name
Description
MFG CO.
'PIC16CR58A-04I/SO' PDF : 217 Pages View PDF
PIC16C5X
7.2 Oscillator Configurations
7.2.1 OSCILLATOR TYPES
PIC16C5Xs can be operated in four different oscillator
modes. The user can program two configuration bits
(FOSC1:FOSC0) to select one of these four modes:
• LP: Low Power Crystal
• XT: Crystal/Resonator
• HS: High Speed Crystal/Resonator
• RC: Resistor/Capacitor
Note: Not all oscillator selections available for all
parts. See Section 7.1.
7.2.2 CRYSTAL OSCILLATOR / CERAMIC
RESONATORS
In XT, LP or HS modes, a crystal or ceramic resonator
is connected to the OSC1/CLKIN and OSC2/CLKOUT
pins to establish oscillation (Figure 7-3). The
PIC16C5X oscillator design requires the use of a
parallel cut crystal. Use of a series cut crystal may give
a frequency out of the crystal manufacturers
specifications. When in XT, LP or HS modes, the
device can have an external clock source drive the
OSC1/CLKIN pin (Figure 7-4).
FIGURE 7-3:
C1(1)
CRYSTAL OPERATION
(OR CERAMIC RESONATOR)
(HS, XT OR LP OSC
CONFIGURATION)
OSC1
PIC16C5X
XTAL
RS(2) OSC2
C2(1)
RF(3)
SLEEP
To internal
logic
Note 1: See Capacitor Selection tables for
recommended values of C1 and C2.
2: A series resistor (RS) may be required for
AT strip cut crystals.
3: RF varies with the crystal chosen (approx.
value = 10 MΩ).
FIGURE 7-4:
EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR LP
OSC CONFIGURATION)
Clock from
ext. system
Open
OSC1
PIC16C5X
OSC2
TABLE 7-1:
CAPACITOR SELECTION
FOR CERAMIC RESONATORS
- PIC16C5X, PIC16CR5X
Osc Resonator Cap. Range Cap. Range
Type
Freq
C1
C2
XT
HS
Note:
455 kHz
2.0 MHz
22-100 pF
15-68 pF
22-100 pF
15-68 pF
4.0 MHz 15-68 pF
15-68 pF
4.0 MHz
8.0 MHz
16.0 MHz
15-68 pF
10-68 pF
10-22 pF
15-68 pF
10-68 pF
10-22 pF
These values are for design guidance only.
Since each resonator has its own charac-
teristics, the user should consult the reso-
nator manufacturer for appropriate values
of external components.
TABLE 7-2:
CAPACITOR SELECTION
FOR CRYSTAL OSCILLATOR
- PIC16C5X, PIC16CR5X
Osc Resonator Cap.Range Cap. Range
Type
Freq
C1
C2
LP
32 kHz(1)
15 pF
100 kHz 15-30 pF
200 kHz 15-30 pF
15 pF
30-47 pF
15-82 pF
XT
100 kHz 15-30 pF 200-300 pF
200 kHz 15-30 pF 100-200 pF
455 kHz 15-30 pF 15-100 pF
1 MHz
15-30 pF
15-30 pF
2 MHz
15-30 pF
15-30 pF
4 MHz
15-47 pF
15-47 pF
HS
4 MHz
15-30 pF
15-30 pF
8 MHz
15-30 pF
15-30 pF
20 MHz
15-30 pF
15-30 pF
Note 1: For VDD > 4.5V, C1 = C2 ≈ 30 pF is
recommended.
2: These values are for design guidance only.
Rs may be required in HS mode as well as
XT mode to avoid overdriving crystals with
low drive level specification. Since each
crystal has its own characteristics, the user
should consult the crystal manufacturer for
appropriate values of external components.
Note:
If you change from this device to
another device, please verify oscillator
characteristics in your application.
© 1998 Microchip Technology Inc.
Preliminary
DS30453B-page 33
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